Moth balls, made of naphthalene, do work to remove squirrels from an attic, but only for a short while. The smell of moth balls quickly fades, and the squirrels come back.
Moth balls should be placed in the attic in order to chase squirrels away. When they are gone, any holes in the attic must be repaired and any food the squirrels were eating must be removed or the squirrels will return.
Moth balls are highly poisonous to people and pets. Anyone with small children, dogs or cats should not use moth balls as a squirrel repellent.
There are far more potent and less hazardous squirrel repellents than moth balls. These include rags soaked in ammonia or human urine or spraying the attic with pine-scented cleaner diluted in a gallon of water.